jfh@rpp386.cactus.org (John F Haugh II) (02/14/91)
in various system v's the cblock freelist is declared
something like
struct chead cfreelist;
and (struct chead) is
struct chead {
struct cblock *c_next;
int c_size;
int c_flag;
}
what the hell is cfreelist.c_size =supposed= to contain? it
sure doesn't contain the total number of characters available
on the cblock freelist right now. my x.29 tty driver thanks
you ...
ps - no fair peeking at the source code.
--
John F. Haugh II UUCP: ...!cs.utexas.edu!rpp386!jfh
Ma Bell: (512) 832-8832 Domain: jfh@rpp386.cactus.org
"I've never written a device driver, but I have written a device driver manual"
-- Robert Hartman, IDE Corp.boyd@necisa.ho.necisa.oz.au (Boyd Roberts) (02/15/91)
In article <19050@rpp386.cactus.org> jfh@rpp386.cactus.org (John F Haugh II) writes: > >struct chead { > struct cblock *c_next; > int c_size; > int c_flag; >} > `c_size' contains the size of the cblock data in bytes (ie CLSIZE). The only reason I could think of them doing this is to enable dynamic sizing of the cblocks. Boyd Roberts boyd@necisa.ho.necisa.oz.au ``When the going gets wierd, the weird turn pro...''
jfh@rpp386.cactus.org (John F Haugh II) (02/19/91)
In article <2022@necisa.ho.necisa.oz.au> boyd@necisa.ho.necisa.oz.au (Boyd Roberts) writes: >`c_size' contains the size of the cblock data in bytes (ie CLSIZE). I knew that much - I wanted to know "why". >The only reason I could think of them doing this is to enable dynamic >sizing of the cblocks. This seems to be one of the commonly given reason. I've not read the more recent AT&T device driver writer's guides to know what they have to say. The XENIX device driver supplement gives 'c_size' as the buffer size, but isn't specific about cfreelist.c_size, which is actually a different structure type anyhow ... Thanks for all of your responses. My X29 tty driver is doing much better now, thank you ;-) And the "crash" command that I posted 3 years ago will be reposted Real Soon Now with enhancements for figuring some of this stuff out. -- John F. Haugh II UUCP: ...!cs.utexas.edu!rpp386!jfh Ma Bell: (512) 832-8832 Domain: jfh@rpp386.cactus.org "I've never written a device driver, but I have written a device driver manual" -- Robert Hartman, IDE Corp.